Abstract: A tubejoint for a heat exchanger made of two dissimilar materials is provided wherein the tubeplate joint is manufactured by use of an explosive having a detonation velocity more than 120 percent of the sonic velocity of the tube materials to be welded. Very satisfactory welds are formed at subsonic velocity between the surfaces of concentric tubes made of dissimilar metal and along the surface of a counterbore formed in the hole in which the composite tube is placed. The joint thus formed prevents any corrosive fluid on the tube side of the joint from coming in contact with any non-compatible material on the shell side of the heat exchanger and also prevents any corrosive fluid on the shell side of the heat exchanger from coming in contact with incompatible material on the tube side of the heat exchanger.